Age resistant rubber hydrochloride



Patented Apr. 28, 1942 I 2.212143% AGE RESISTANT RUBBER HYDROCHLORIDE Albert Hershberger, Buflalo, N. Y., assignor to du Pont de Nemours a. Company, Wiln, DeL, a corporation of Delaware No Drawing. Application March 2, 1940, Serial No. 321,984

14 Claims. This invention relates to rubber hydrohalides,

especially rubber hydrochloride. More particu-.

larly it relates to thin sheets of rubber hydrochloride which do not readily deteriorate.

Rubber, having the formula:

drogen chloride to form a product called rubber hydrochloride, having the formula:

(-CHs--CHs-CHr) in which a is a positive integer, as indicated in J. I. E. C. m 125, Paper Trade Journal February 23, 1939, page 96, and the literature cited therein. The addition of the chlorine radicals can be readily regulated to produce products of various chlorine contents. Materials analyzing 26%-34% chlorine are distinctly diflerent from rubber and are now available on a commercial scale.

Rubber hydrochlorides and the corresponding other rubber hydrohalides deteriorate rapidly upon aging, exposure to light, and subjection to elevated temperatures. This deterioration which may include photochemical disintegration,- is perhaps the'principal reason why the material has not gone into a Wider use, particularly in the sheet wrapping material field.

This invention has for an object the preparation of rubber hydrohalide products, particularly rubber hydrochloride sheet wrapping materials which would not becomebrittle and/or fragile and/or dark-colored upon aging for long periods of time in the presence of air and/r upon, subjection to elevated temperatures and/or upon exposure to light. The preparation of light, heat and age resistant rubber hydrochloride compositions suitable for sheets, continuous webs, filament solutions, coating compositions, molded articles and the like, constituted other objects. Another oblect was to prepare rubber hydrochloride articles stabilized with stearic acid salts of ammonia derivatives and the like. Still other objects were to provide a new class of materials for increasing the resistance of rubber hydrochloride to the action of both light and heat, and to provide light and heat resistance to rubber hydrochloride compositions suitable for use in the preparation of sheets, filament solutions, coating compositions, molded articles, and the like. A general advance in the art, and other objects which will appear hereinafter, are also contemplated.

' It has now been found that resistant rubber hydrochloride compositions and/or articles can be produced bystabilizing rubber hydrochloride with long chain fatty acid salts oi aliphatic radical substitution derivatives 01 ammonium hydroxide.

, From the following description and specific examples, in which are disclosed certain embodi-' ments ofthe invention as well as details of what is believed to be the best mode for carrying out the invention, it will be apparent how theioregoing objects and related ends are accomplished. The parts are given by weight throughout the application.

Example I ing clear solution on a chromium plated steel 'plate, and dried at about 40 C. The resulting films, after stripping from the plate, were apfilm heated at C. in

proximately 0.001 of an inch thick. They were flexible, transparent and strong. Strips oi the the dark retained good film properties during 47 days. Films cast from some of the rubber hydrochloride solution to which no stabilizer had been added became embrittled after 15 days.

Example 11 To .a 6% solution (in chloroform) of rubber hydrochloride there was added 10% (based on the weight of the rubber hydrochloride) oi benzyl-tri-methyl-ammonium-stearate. Higher or inch thick prepared from the above room aging conditions in indirect sunlight. Corresponding films prepared from the unmodified rubber hydrochloride were quite brittle after 30 days exposure under the same conditions.

Example III To a 5% solution (in chloroform) of rubber hydrochloride, (based on the weight of the rubber hydrochloride) of methyl-propyl-ammonium-oleate was added. The stabilizer dissolved readily in the solution. The resulting rubber hydrochloride composition was found to Example IV To a 5% solution in chloroform ofrubber hydrochloride.was added 7% (based on the weight of the rubber hydrochloride) of di-butyl-amine (ammonium) laurate, which dissolved readily in the solution. Transparent, self-supporting films approximately 0.001 inch thick were prepared from the above composition by solvent evaporation. These films retained in large measure their flexibility, tensile strength and toughness for 62 hours under room conditions when exposed to a sun lamp. Similar films of unmodified rubber hydrochloride became quite brittle after 40 hours exposure under the same conditions.

Example V The process of Example 11 was repeatedwith another batch of rubber hydrochloride. The results of aging were as follows:

Bun- Fadeomefer Day- C. Stabnm' 'lamp 0. v. 1mm) light dark Hours Home Dow Day: I Blank (no stabilizer) 40 30 i6 Benzyl-tri-methylammonium atearato 52 64 4 7 The stabilizing effect of the ammonium hydroxide derivatives is clearly illustrated by these figures (for one such derivative) which give the time elapsing before embrittlement was observed.

In the preparation of the compositions of this invention, it is preferable to employ a neutral rubber hydrochloride from which free hydrogen chloride (if any) has been removedrby any suitable method, for example, by washing the rubber hydrochloride with methanol, by treatment of the rubber hydrochloride (which may be in solution) with basic material such as alkali carbonates, hydroxides, oxides and the like, alkaline earth carbonates, hydroxides, oxides and the like,

with organic amines and the like, followed by removal of the basic material (and its salt).

The amount of the stabilizer ordinarily used falls within the range 0.5% to 12%, based on the weight of the rubber hydrochloride. Theintermediate range of 1% to 10%; and usually the still more specific range of 1% to 5%, has been found preferable. For special purposes more than 12% may be used.

In the preparation of transparent films from pounds but rubber hydrochloride compositions containin the stabilizer, it is preferred that the stabilizer be comps tible with the rubber hydrochloride and be used in an amount which is compatible with the rubber hydrochloride. that it be soluble in solvents for rubber hydrochloride (chloroform,.carbon tetrachloride, benzene, toluene, methylene chloride and the like). When transparency is not essential, it is not necessary that the stabilizer be completely compatible with the rubber hydrochloride or that it be used in an amount which is compatible with the rubber hydrochloride.

The preferred ammonium hydroxide substitution derivative stabilizers are methyl-propyl ammonium oleate, benzyl-tri-methyl-ammonium stearate and di-butyl-ammonium laurate.l The stearic acid salts of ammonium hydroxide derivatives are preferred as a sub-class.

The alky l(used to include aralkyl) substitution derivatives of ammonium hydroxide of the present invention are comprehended by the general formula: 'i a i W-N-Y t I in which W, X, Y and Z are hydrogen or alkyl.

The aliphatic acids employed contain 12 to 20 carbon atoms. Acids containing more than 20 carbon atoms are useful for special purposes.

The salts in which one or more of the radicals W, X, Y and Z are aryl groups are (in general) not as effective as the corresponding alkyl comthey are far superior to the stabilizers known to the art. When there is an alphyl carbon atom between an aryl group and the nitrogen atom, the resulting (aralkyl) ammonium salts act like or behave comparably with the alkyl ammonium salts.

The stabilizers may be used singly or in combination.

The stabilizer may be introduced into the rubber hydrochloride composition in any suitable manner, for example, by the use of a neutral solvent, by milling, by grinding or kneading, and the like.

The rubber hydrochloride may be prepared by any of the various methods known to the art, for example, by the addition of gaseous hydrogen chloride to rubber dissolved in a chlorinated solvent, by the treatment of rubber with solutions of substantially anhydrous hydrogen chloride in a non-solvent for the rubber (ethyl acetate and the like), by the reaction of rubber with liquid substantially anhydrous hydrogen chloride at low temperatures (such as -80 C.) and the like.

Complete saturation with hydrogen chloride is not necessary to produce a useful and important material. The rubber hydrochloride employed preferably has a combined chlorine content of 28% to 32%, but comparable results are obtained with material whose chlorine content is within the range 26% to 34%.

Either amorphousqor crystalline varieties, or mixtures of these varieties, may be employed. Mixtures of rubber hydrochlorides of different chlorine contents may be employed, for example, various production batches may be blended.

One very desirable method for preparing the rubber hydrochloride is tosaturate (at room temperature) a 3% solutioniin chloroform) of 30 minute milled pale crepe rubber with dry hydrogen chloride, andto thereafter pass additional hydrogen chloride into the solution for 48 hours It is also preferred (with stirring). The resulting solution is then pouredslowlyintoalargeexcessofmethanol, whereby the rubber hydrochloride is precipitated. 'l'heproductisthenwashedwithmethanolimtil the washings are neutral to bromthymol. For convenience in the rubber hydrochloride may then be redissolved in chloroform to produce a solution. fIhe chlorine content 01' this rubber lrvdrochloridershould be 30.5%v to 31.5%.

The new compositions may also contain, in addition to the stabilizing material which curbs or restrains the deterioration, modifying agents such as natural resins, synthetic waxes, wax substitutes, wax-like materials, wax blending agents, oils, y n oils. driers, fats, and-static agents, slip agenB, Pi ments. metallic powders. fillers, dyes, plasticizers, etc. Minor proportions or other film iormingmaterials and stabilizers, singly or in combination, may be employed.

Compositions of glass-clear iransparency can readily be prepared according to this invention, because of the excellent solubility and compatibility oi the stabilizers. The stabilizers cause no substantial change in the film-forming properties of the rubber hydrochloride, and may. for

this reason, he used in larger amounts (it this is desirable considering the specific purpose towhich the composition is to be put) thanstabilizers heretofore proposed in the art. An additional advantage for compositions of this invention resides in the fact that the stabilizes do not evaporate from the compositions. as a re suit, the compositions retain their resistance to light and heat over long periods of time, a characteristic heretofore unhown because the only organic stabilizers were considered suitable for rubber hydrohalida were volatile.

Rubber hydrochloride compositions containing long chain aliphatic acid salts of slhl substitution derivatives of ammonium hydroxide may be disolved in olvents in any manner known to the art, and may be used in the preparation of transparent sheeting for wrapping protective coatings and the ike. The compositions may he milled for the purpose oi reducing the viscosity of the composition in order to obtain a high solids coating composition. In addition, these rubber hydrochloride compositions may be rolled and calendered into sheets or molded under heat and pressure into articlm oi commerce. .Ehe compositions may be used for lamination by heat and pressure or with adhesivm, and for the coatins oi paper, sheets oi regenerated cellulose, transparent sheets and films oi all thetic or naimral andiihem, Wood, Slim 63311118 ma I r thelikaandmaybeusedasves.

A multitude of other uses for hydroarewell a my} chloride mowntotheartmninecdnot berepeatedhere. Thecompositionsoithemesentinventionaresnitediorthem paratlonofthin (thatiaontheorderoiaiew ten-flaousandthstoa few hundredthsoianinch in thickness) sheet material, particular-lymparent, self-supporting films which are hizhiy durable, tear resistant, and water Films of such compositions rmistor repress the actionoiheatandtheactlonoi'light.'

As many apparently wlddy diiierent embodimentsoithisinvenflonmaybe partinghomthe spifitand 955 ,IIJAJ...

together with at least $592 flamed on the 1 ste.

. ntheberelni'anm sanmbenz immeib ibyemse,

defined in the appended I claim:

1. a composition of mm which includes a 5 rubber hydrohalid weight of benzyi trimethyl ammonium stearate.

with 5% of its 2. A composition of matter which includes a rubber hydrohalide with at least 0.5%

(hasedonthembberhydrochioride) oianalilv phatic acid saltwf benzyi trimeihyl ammonium hydroxide, said aliphatic acid-having 12 to carbon atoms.

3.1hemethodoi'PI-eservingrubDerhydrochloride which comprises heating rubber hydro- 4. A sheet wrapping material comprising essen- 20 tiaily rubber hydrohalide stabilized with 5% of its weight of the benzyl trimethyl ammonium salt of an aliphatic acid having 12 to 20 carbon atoms.

5. A sheet wrapping material comprising essentialiy rubber hydrohalide stabilized with 5% of its weight of the benzyl trimetbyl ammonium salt ot 'an aliphatic acid having more than 12 carbon atoms.

8. Acomliositio'n of matter which includes a rubber hydrochloride stabilized with 5% of its a) weight oi benzyl trlmethyl ammonium s '1. A composition com ementially rubber hydrochloride of 26% to 3% chlorine content together with at least 8.5% (based on the rubber hydrochloride) of an aliphatic acid salt of benml trimethyl o'nium do, said aliphatic acid harms 12 to so carbon atoms.

8. A composition comprising essentially rubber hydrochloride oi 26% to also chlorine content together with at least 9.5% '1 as: on the rubber so hydrochloride) of an aliphatic acid sflt oi benzyl trimethyl ammonim hydromde, said aliphatic 7 acid having more than 12 carbon atoms.

9. A sheet wrap terial comprising essenruhber hydrochloride or 28% to 34% chicnae content together with at least 0.5% d

on the rubber hydroride) of hi trimethyl onium steer-ate.

in. A composition-comp wrubber ydrochloride oi 25% to Mill chlorine content hydrochloride) oi beam trimethyl 11. t pgpinema com msentlally rubber stab with about 5% oiits weight oi l izimetbyl salt of aliphatic w: having more atoms.

dons.

"l cel aliphatic acid having more than 12 14. a compositi tiallyrub r 9.5% o mom]! 

